As is well understood, serial digital-to-analog conversion can be accomplished with the aid of charge storage devices and programmed switching means for selectively coupling the charge storage devices together. More particularly, the programming is so arranged that a fixed input charge (representing a binary 1 or 0) is summed with a pre-existing stored input charge (if any), the combined charges are split in half and one of the split halves is summed with the next input charge, etc., until input charges corresponding to all input serial binary bits have been so processed. The resulting charge in the charge splitter represents the analog value of the serial binary input. Such a technique is described in the book "Electronic Analog/Digital Conversions" by Hermann Schmid, VanNostrand Rhinehold Company, 1970, pages 186 and 187.
It is advantageous to implement the above-described conversion technique with the aid of charge-coupled device technology. Accordingly, diffusions in a semi-conductor substrate are used to generate and to collect charges while insulated gate electrodes spaced from each other along a charge pathway between the diffusions provide the necessary charge storage and charge splitting functions. The gate electrodes must be energized in a predetermined manner to control the operation of the charge-coupled device (CCD) converter. Previously, each input digital signal was decoded to generate the necessary waveforms for application to the gate electrodes. Special control logic was provided to accomplish the required decoding. Such a technique is disclosed in copending patent application Ser. No. 644,000 filed Dec. 23, 1975 in the name of L. M. Terman, for "Digital-to-analog and Analog-to-digital Converter Circuit" and assigned to the present assignee. It is desirable, however, to provide a CCD-instrumented serial digital-to-analog converter utilizing a predetermined sequence of control waveforms for application to the respective gate electrodes independent of the value of the input digital number to be converted.